"Powell, Dan" wrote: > > I have been in RC 12 years. I always went with the MFG recommend prop that > was in stock at the local hobby shop. I have heard several different > opionions on prop selection, but still have confusion. Could somebody please > endow me with theip prop knowledge? > > 1. pitch? > 2. length? > 3. RPM,s > 4. Speed ? > 5. Torque? > 6. model weight? > 7. APC vs carbon vs wood
The motor/engine performs most efficiently within a range of RPM and torque. Pitch and diameter determine the thrust, with 1 inch of diameter making a bigger difference than 1 inch of pitch, so pitch can be used for fine tuning performance. The material of the prop determines the weight, strength, and tracking of the airfoils. A high RPM prop wants to come apart. A high thrust prop wants to bend. Then there are prop performance goals like climbing, or cruising. A climbing prop spins at max RPM where the motor develops the most torque. A cruising prop spins at a lower RPM for max thrust. Altitude also has an effect on the density of the air, so if you live at 5000 above sea level, you are gonna need a prop with more thrust than someone at 200. Electric motors are MUCH easier to match a propellor than gas. Monitor the motor's RPM, current, and voltage, to determine the best range for a prop (most RPM, lowest power draw = current x voltage) by drawing a graph. Note that the static performance of a prop will be less than the dynamic. There are a number of propellor calculators available. These are handy for finding starting points. Do a google search. -- Andrew E. Mileski Ottawa, Canada RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
